i Tunes

I think that the CDs of your own that you've added to iTunes don't transfer, only directly bought ones.

discussions.apple.com/thread/5555168?tstart=0
The above link explains why your own CDs are not on your new machine (see the responses from the contributor called Neil).
Here is a link to help you back up the iTunes library on your old computer so that you can transfer the backup to your new one:-
support.apple.com/en-gb/HT201625
I'm assuming that you haven't backed up to an external drive as you think you could have used iCloud but you would have needed to turn on 'Match' for songs from your own CDs to be in your restored iTunes library.
You could transfer the backed up file from your old computer using a flash drive. Check that the flash drive has enough capacity for the file.
Here is another link that could be useful:- www.imore.com/how-download-all-your-music-icloud-music-library
Sorry for using links but they put over the information better than I can.
This is not simple. I volunteer for a charity that helps people with their IT and it is one of the most difficult areas to tackle.

Thanks for your help. I will use the links and try and follow the instructions. Thank goodness I have still got my old laptop and not thrown it out yet.